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how long can i put the car on idle?

2700 Views 20 Replies 14 Participants Last post by  Jspeed
i never done it, but i've always just wanted to play my PS2 in my car during lunch sometimes, but don't know what the effects are on the battery if i just turn the car and engine on, and leave it idle. (i have a full A/V stereo system with ps2)

usually, on long trips, it hasn't been too bad with the battery playing the ps2 or watching DVD for 2-3 hours at a time, but what about if i just leave the car on in a parking lot for an extended period??
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well..i'll give you an engineering answer...

your car relies on the viscosity of the oil along with speed the rotating parts move for protection. I barrier is formed between the bearing and the wearing surface when it reaches higher rotating speeds.

When sitting idle... (rotation is slow) the barrier slowly depletes until the engine teperature rises to it's maximum idled temperature. I'm not sure exactly what it is for BMW, but i'm guessing around 230°F. When this max temp is reached, the oil's viscoty is the lowest....or in other words the oils is thinner (like water)

sitting at idle for a long time.... only increases the ammount of wear on the bearing surfaces. Your car should not overheat.... only wear its parts faster.

You could probably idle through 10 tanks of gas and not notice any difference. You however, may lose about 10K miles off the life of your engine.

hope this helps a little.
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VIK AD said:
Just my two pennies worth...

We all should have a radiator at the front of the car, plus various intakes for cold air. My understanding is that when the car is in forward motion, this air get drawn into the radiator slats, to cool the temperature of the water (most of our cars should be water or air cooled or both). :)

Therefore, if the car is not moving, there is a likeliness that the engine will heat more than normal - possibly causing overheating and therefore, potential damage. This could be directly related to a lesser supply of air to cool the water, which is driven around the engine for cooling. We do have a cooling fan. But, it is not sufficient to cool the engine for a sustained period of non-motion.

Vik AD
Your radiator also has fans infront of it which are triggerd by a temperature switch. The fans will only be ineffective if you are revving the engine... say 4K rpms without moving. 99% of cars are designed not to ever overheat at idle, ever.

Now... as far as how long you should let it idle to warm it up.. in the BMW owners manual i believe it says "Dont".

This is ofcoarse weather dependent... if it's -10°F outside... I'd say you should let it idle for about 2 minutes to get the oil warmed up. IF it's a 70°F day out... you should be able to drop it in gear as soon as you start it.
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